Management of different types of resources (such as software components, applications or devices) is a critical issue in a data processing system with a distributed architecture. This problem is particular acute when the system includes a high number of logical and/or physical entities (referred to as subjects), each one controlling different resources; the problem is further exacerbated if the subjects have a high level of complexity or are dispersed across a large number of installations.
The management environments known in that art are typically based on an enforcement model (also known as manager/workers model). In this model, the process is entirely controlled by an authority residing at a central site of the system. The authority defines a desired configuration of every subject. For this purpose, the authority accesses a central repository storing the (alleged) current configuration of each subject, and determines the management actions required to bring the subject to the desired configuration starting from its current configuration. The management actions are then enforced remotely by the authority on the subject (which is totally passive).
A different approach is proposed in WO-A-2003EP10081; this document discloses an autonomic management system, wherein each subject self-adapts to the corresponding desired configuration. For this purpose, the authority publishes a set of rules into a shared repository; each rule specifies the desired configuration for a category of subjects (defined according to their physical/logical characteristics). Each subject retrieves and applies the corresponding rules directly. In this way, the subjects are no longer passive entities but they actively participate in the configuration process. As a consequence, it is possible to avoid inconsistencies and support subjects that are not available or off-line. In the above-described solution the control of the environment is fully automated and delegated to the subjects (with a system administrator that is required to intervene only when a malfunctioning occurs or when some subjects are unable to comply with the corresponding rules).
Nevertheless, in different practical situations it would be desirable to have some sort of centralized control on the operations that are performed on the subjects.
A typical example is that of an organization moving from a resource management system based on the enforcement model to one based on the adaptive model. In the above-mentioned scenario, it is useful for the system administrator to be able to control the migration process; in this way, it is possible to implement a gradual transition between the two different resource management models.
It should be noted that those requirements are completely incompatible with the adaptive nature of the resource management system described in the cited document. Therefore, any attempt to provide some sort of centralized control risks disrupting the proposed model.
This problem is particular acute in large systems with several correlated tiers, wherein a solution to be deployed in the system is very complex; therefore, any changes in the definition of the solution should be avoided since their effects can be unpredictable.